Glaucoma, a widespread, chronic disease, is a leading cause of blindness and is related to the death of retinal ganglionic cells. In the most prevalent form of glaucoma, primary open-angle glaucoma (POAG), increased intraocular pressure (IOP) is the most common risk factor associated with the loss of retinal cells. Results from large clinical trials indicate that decreasing IOP in glaucoma patients delays the development of vision loss. Even glaucoma patients with IOPs in the normal range benefit from decreasing their IOP. Currently, numerous pharmacological and surgical approaches are employed to reduce IOP in glaucoma patients. However, drug treated patients are frequently noncompliant, refractory and/or suffer from adverse effects. Current surgical implants are passive devices unable to detect or respond to changes in IOP and frequently fail. With either approach, a patient office visit is required for the physician to manually verify IOP control by tonometry. We propose to create an implant capable of both sensing IOP and regulating it through opening and closing a miniature valve. The implant's power supply will be self-contained, with a transceiver capable of sending and receiving external commands. In its final form the implant will monitor and regulate IOP and be capable of recording and sending IOP data and information concerning valve function to the physician and/or patient via a digital device such as a PC. The three specific, measurable objectives for Phase II are to: 1) Design and fabricate a miniature twin magnetic stop/electromagnetic valve with accompanying telemetry and data acquisition system. 2) Perform short and long-term in vitro tests of the valve to demonstrate detection, response and control of IOP in the normal and pathological pressure ranges. 3) Implant the valve and test it both acutely and chronically on conscious, active normal IOP rabbits to determine safety and efficacy.